Pest identification, please?

blissfulgarden(8b)September 14, 2008

Alrighty, I expect to lose about 1/2 of my 220 varieties this first year due to climate here in the south. I've got my first rotter in the group, and I need help identifying the pest I found within. The iris is Viva Mexico and I purchased the rhizome from a grower in Mississippi. It is one of only two problem rhizomes at the moment, which I think is pretty good considering the tremendous rain and humidity we have had. The other problem rhizome, Broken Record, was damaged when received, so it was iffy at best. I believe these could be immature borers in the base of the Viva Mexico, but as I've never seen a true borer, I can't be sure. They could just be caterpillars. So... identification help, please? Thanks for any feedback you can provide! Ev :)

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wmoores(7/8 MS)

I do not know what the creature is, particularly if you got the plant from MS. I have had an occasional borer shipped in from up East but was dead in transit because of the heat build-up in the box. Borers do not survive this far south. I have had an occasional earqwig chew on blooms but have never seen any larvae of any insect on irises.

Your loss rate will be greatly reduced it you keep granulated terraclor on the rhizome and base of the fan. What you applied earlier may have splashed out because of the rains. It is ok to add more. It doesn't affect the growth or bloom of the plant. You may also have to do add more when you unpot.

I have 85 potted irises and all pots have received two doses of terraclor. No plants have shown any inclination to rot and we have had excess rain from Hurricanes Fay, Gustav, and Ike. Most of our rainfall came with Fay and the ground has been saturated for over a month now.

    Bookmark   September 15, 2008 at 6:10AM
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Thanks for the feedback, Walter! I'll add the extra dose of terraclor today. I did mist them all down with a clorox solution after their time in the storeroom during Gustav, but I haven't treated with more terraclor. Should I spray with a general insecticide as well? I'm uncertain what would be most effective since I can't identify this particular pest.

    Bookmark   September 15, 2008 at 10:20AM
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marvine(z7/8 GA)

Terraclor?? I'm not familiar with it, did a search and am told that it is no longer on the market. Is there a similar product?

    Bookmark   September 15, 2008 at 4:46PM
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Yes, terraclor is the former brand name for PCNB. Here is more detailed information about it:

I used the granular form as an additive when mixing my potting soil and will add more on top per Walter's suggestion. I also plan to add it when transferring my plants from the pots to the garden in October.

    Bookmark   September 15, 2008 at 5:35PM
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wmoores(7/8 MS)


I just don't have enough insect damage to worry about. Some years grasshoppers are worse than normal. Aphids and thrips used to be a minor problem, but I think the Dial soap spray suffocates any larvae and eggs that might be on the foliage since it sticks until the next rain.

You may read or hear that insects transmit rot and scorch, but I believe that to be an old wives' tale. Scorch is totally unpredictable and the cause unknown. Occasionally, you can save an infected plant; mainly they die no matter what you do. I had one to recover on its own this summer. This is a minor problem in the south, and out of 1,500 plants (including sdlgs.), I had about ten random cases of scorch scattered throughout the garden. If I have a sdlg. clump I am watching, I will take a butcher knife and cut through the clump to separate it, so that if scorch strikes, it will not take the entire clump. I have seen lots of clumps half scorched. One side dies and the other lives. Weird, but that is why I cut some of my sdlgs. in two when they are big enough to do so. I think if an insect chewed on the clump and carried scorch, it would take out the entire clump since the rhizomes are all connected. It could be that the scorch 'virus' doesn't pass through the spent mother rhizome, and that it why it may appear only on one side of a clump.

    Bookmark   September 16, 2008 at 6:23AM
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irisqueen217(7b-8a TX)

You can google iris borer photo, and there are plenty of pics. If I had to guess, I'd say that looked like larva borers, but it's just a guess. :) -Liz

    Bookmark   September 21, 2008 at 6:02PM
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Thanks for the info, Walter. You are offer such a wealth of good advice!

Liz, that's what I thought too. But, I could only find photos of adult borers. Blah! Has anybody seen the little guys in person before?


    Bookmark   September 25, 2008 at 6:53PM
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